Color television tube



y 17, 1956 I J. F. WILHELM 2,755,405

COLOR TELEVISION TUBE Filed Oct. 15, 1953 INVENTOR.

United States Patent CQLOR TELEVISION TUBE John F. Wilhelm, Lancaster,Pa., assignor to Radio Corporation of America, a corporation of DelawareApplication October 15, 1953, Serial No. 386,167

Claims. (Cl. 3'1392) This invention relates to improvements incathode-ray tubes and to improvements in the art of manufacturing thesame.

In the art of manufacturing glass cathode ray tubes of the colorkinescope type certain difliculties are encountered. One of theprincipal difficulties arises due to the fact that optimum performancecan be achieved only when the gun elements and the target, or screenelements, are mounted in substantially perfect alignment. In order fortubes of this type to be manufactured in large numbers and utilizingmass production techniques, this alignment must be accomplished in avery simple manner.

There are presently available several known methods of supporting thegun, or battery of guns, in glass envelopes that satisfy therequirements of mass production. However, when using glass envelopesmany problems remain in the presently available means of support for thetarget assembly. Some of these latter problems are: simplicity of thesupport members, to permit manufacturing in large quantities without thecost thereof being a prohibitive factor; strength of the supportmembers, to insure rigidity of the target when the tube is moved; easeof assembly, to permit the use of non-skilled labor when assembling thetubes; expansion characteristics of the target support means mustsubstantially match the expansion characteristics of the glass envelopeand the target or, in the alternative, the support means must beconstructed to permit differences in the expansion characteristics, toavoid undue stresses and strains in the various elements; and, thetarget support means should be of a type that would not require extrasteps in the assembly of the tube such as orientation of the target.

It is therefore an object of this invention to provide a new and novelmeans to support a target in a glass envelope of a tri-color cathode raytube.

It is another object of this invention to provide a tube structure whichshall lend itself readily for use in mass production of color kinescopesof the glass envelope type.

It is a further object of this invention to provide a method of andmeans for aligning a screen assembly of the masked target variety withrespect to an electron gun, or a battery of guns, in a glass envelopefor a color television cathode ray tube.

The foregoing and other objects are accomplished in accordance with thisinvention by providing a mount for a tri-color screen assembly in aglass bulb which includes a plurality of glass registry-support means inthe funnel portion of the glass envelope, and matching support means inthe glass face panel portion of the envelope. Placed between the supportassemblies is a spring mount for the tri-color target, or screen,assembly which supports the screen assembly in rigid suspension withinthe envelope. In the alternative the glass face panel may be so shapedas to engage a spring mount whereby a restraining influence is exerted,and the tri-color screen assembly is held in suspension within theenvelope.

The novel features which are believed to be characteristic of thisinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof willbest be understood by reference to the following description when readin connection with the single sheet of accompanying drawings in which:

Figure 1 is a diagrammatic view of a cathode ray tube utilizing a glassenvelope;

Figures 2 through 4 are enlarged fragmentary sectional views of acathode ray tube each utilizing an embodiment of this invention;

Figures 5 and 6 are enlarged fragmentary sectional views of embodimentsof the target support means in accordance with this invention; and

Figure 7 is a diagrammatic view of an end of a cathode ray tube showingpossible orientation of the support means in accordance with thisinvention.

Referring in detail to Figure 1, there is shown a diagrammatic View of acathode ray tube 10 of the tri-color kinescope variety. The glassenvelope of tube 10 comprises a hollow glass frustrum portion 12 havinga glass face panel 14 sealed across the larger of the two apertures,

and a glass neck 16 sealed across the smaller aperture.

Enclosed within the neck portion 16 is an electron gun, or battery ofguns, 18 which may be any of the conventional types of electron guns.Arranged closely adjacent the glass face panel 14 is a target assembly20. The target assembly 20 may be of the masked target variety whereinthe correct spacing between the thin metal mask, and the alignment ofits apertures with respect to the color emitting phosphor elements maybe fixed by a suitable frame or other spacing elements during themanufacture of this sub-assembly in the manner taught in U. S. Patent2,625,734 granted to H. B. Law on January 20, 1953. In the alternativethe target assembly 20 may include only the shadow mask while the coloremitting phosphors are supported on the face panel 14. When the latterarrangement is utilized the shadow mask is curved to equal the radius ofcurvature of the glass face panel 14. The alignment of the shadow maskand the phosphors in the latter arrangement are described hereinafter.For purposes of this invention it is assumed that the battery of guns 18has previously been aligned with respect to each other as a separatesub-assembly.

Even though the battery of guns 18, have been previously aligned onewith the other there remains the problem of alignment, or registration,of the target assembly 20 with the electron guns 18. In other words theentire target assembly 20 must be located within the envelope in such amanner as to have the electron beams from guns 18 bombard the target 20in the proper location. The solution of this alignment problem iscomplicated by the fact that certain types of elements are excellentsupport members but they are subject to movement when heated due toexpansion and contraction as a result of variations in temperature. Anymovement of the target assembly 20 is undesirable in that the electronbeams will no longer land on the correct areas of the target.Furthermore, if metal elements of conventional design are used tosupport the target assembly 20, differences in the coefiicient ofexpansions of the metal support members and the glass portions of theenvelope are likely to produce strains and cracks in the glass at pointswhere the metal touches glass.

Referring now to Figure 2 there is shown an enlarged fragmentary view ofa support structure for the target assembly 20 in accordance with thisinvention. In this embodiment of the invention the target assembly 2% issupported by a plurality of circumferentially spaced spring elements 22which are supported between a plurality of circumferentially spacedglass protuberances, or posts 24 on the glass frustrum 12 and aplurality of circumferentially spaced protuberances, or posts 26 on theglass face panel 14. For simplicity in the drawings only one supportmeans is shown in Figures 2 through 6. The spring elements 22 may be ofa material such as tungsten or high grade steel, or the like and areconnected to the frame 30 of target assembly 20 by a weld 28 or othersimilar bonding operation. The glass support posts 24 and 26 on thefrustrum 12 and face panel 14 respectively may be formed as the glass ismolded, or as an alternative, the glass posts or protuberances 24 and 26may be added after the frustrum 12 and face panel 14 have been formed bybeing fused or by other conventional means of bonding glass-to-glass.

Each of the glass posts 24 and 26 preferably includes a grooved portion24 and 26 respectively into which the springs 22 snap fit and thusprevent movement of the springs 22 whereby any rotation of the targetassembly 20 is eliminated. The springs 22 may extend into the targetassembly 20 as shown adjacent post 24 as long as the springs 22 do notinterfere with the elements included within the target assembly 20 anddo not interfere with the elements included within the target assembly20 and do not extend out to a point where they will be seen when thecathode ray tube is in operation. The number and location of the springs22 and posts 24 and 26 will be discussed hereinafter.

When practicing this invention the assembly of the cathode ray tube 10may be as follows: When the glass frustrum 12 is molded a plurality ofposts 24 are also molded at various circumferentially spaced locationsaround the axis of the envelope. During the process of molding the glassface panel 14 the glass posts 26 may also be molded at spacings to matchthe locations of posts 24. When the neck portion 16 is sealed to thesmaller aperture of the glass frustrum 12 the battery of electron gunsare aligned with respect to a particular spot on the frustrum 12. Onesuch spot could be one of the glass posts 24. When these steps have beencom pleted and the plurality of springs 22 bonded to the frame 30 forthe target assembly 20 by a weld 28, the springs are snapped in thegrooves 24 of posts 24 on the glass frustrum 12. At this time the glassface panel 14 is placed on top of the springs 22 and pressed until thefrustrum 12 and face panel 14 are in contact. The elements are held inthis relation until a suitable vacuum tight seal is made between thevarious glass portions. By pressing on the frustrums 12 the targetassembly is actually held in suspension by means of the springs 22.

The seal between the frustrum 12 and face panel 14 is preferably a lowtemperature seal to avoid damaging, by heat, the various phosphorparticles in the target assembly 20. One such low temperature seal isthe type of seal obtained when a low melting point glass is used as afrit. In the alternative a thin metallic coating may be applied to theglass and a radio frequency current seal utilized. When these seals areutilized a vacuum seal may be made at temperatures in the order of 400C.

Due to the fact that no portion of the target assembly 20 is in directcontact with any portion of the glass supporting means, and due to theresilient action of the springs 22, expansion and contraction of thevarious elements is immaterial in that any expansion or con traction ofthe elements is absorbed by the resilient properties of the springs 22.Thus, even though the target assembly 20 expands, no movement of thetarget assembly as a whole occurs but merely greater compression ofsprings 22. When the target assembly contracts the springs 22 are lesscompressed and the target assembly as a whole remains in the sameposition.

When the phosphor particles are placed directly on the face panel 14 thealignment between the phosphor particles and the shadow mask is obtainedby selecting a predetermined spacing between these elements. After thespacing has been determined the size of springs 22 is selected so thatwhen the springs 22 are under compression within the envelope, i. e. thesnap fit is obtained, the correct spacing is automatically obtained.

Referring now to Figure 3 there is shown an enlarged fragmentary view ofan embodiment of this invention. In this embodiment the frame 30 whichsupports the apertured shadow mask 31 of the tri-color screen assemblyare supported by being placed between springs 32 and springs 34. Thesprings 32 are arranged to snap fit into grooves or apertures in theposts 26 on the face panel 14 as was described above. The springs 34 areof the type shown and are locked into position by having one end snappedinto grooves 25 in posts 24 on the glass frustrum 12. Due to the factthat springs 34 are locked to the posts 24 rotary movement of the targetassembly about the axis of the tube is eliminated. Due to the tensileproperties of springs 32 and 34 movement of the target assembly alongthe axis of the envelope is also eliminated.

The assembly of this embodiment is substantially the same as thatdescribed in connection with Figure 2 except for the presence of thelocking grooves 25 in the support posts 24. The locking grooves 25 maybe formed in the glass posts 24 when the frustrum 12 is molded, or at alater time. The springs 34 are preferably attached to the posts 24before the tri-color screen frames 30 are inserted to avoid as muchstress on the frames 30 as is possible whereby damage to the phosphorsis prevented. The phosphor particles (not shown) may be supported by theframe 30 or may be supported by face panel 14 as desired.

Expansion and contraction of the various elements shown in Figure 3 isabsorbed by springs 32 and 34 substantially the same as was described inconnection with springs 22 of Figure 1. Therefore, further descriptionthereof is not deemed necessary at this time.

Referring now to Figure 4 there is shown a fragmentary sectional view ofan embodiment of this invention wherein the target assembly 20 issupported entirely within the front face panel 14. In this embodimentthe face panel 14 includes a plurality of locking slots, or gutters, 40and 41. The locking slots 40 and 41 may be formed when the face panel 14is molded or may be cut thereafter and are preferably just large enoughto receive the curved ends of spring 44 so that rotary movement of thetarget assembly 20 around the axis of the tube is eliminated. Thesprings 44 may be attached to the target assembly by a weld 43, or bybeing bolted or fitted.

In the embodiment of Figure 4 the battery of electron guns 18 arealigned in the neck 16 with respect to a particular spot on the glassfrustrum 16. When the springs 44 have been locked into position in theface panel 14 the target assembly is locked into position. If the sealbetween glass frustrum 12 and glass face panel 14 is now made the guns18 are automatically aligned with the elements of the target assembly20.

In any of the embodiments of the invention shown in Figures 2 through 4it should be understood that the target assembly 20 may comprise thethree color emitting phosphor particles, the shadow mask 31 and thetarget frame 30. Or, in the alternative, the phosphors may be placed onthe inner surface of the face panel 14 and the target assembly includesonly the shadow mask 31 and the mask frame 30. When the latterarrangement is utilized the shadow mask is preferably curved (not shown)to match the radius of curvature of the face panel 14.

Referring now to Figure 5 there is shown a modification of the inventionwherein a spring 50 is joined to the extended surface of the targetassembly 20 by welds 51 and 52. In this modification the spring 50 maybe connected to frame 30 of the target assembly by means of bolting orfitting as an alternative to welds 51 and 52. When the target assemblyis fitted into an envelope similar to that shown in Figure 1 the targetassembly 20 will be in suspension as was explained previously.

Referring now to Figure 6 there is shown a modification of thisinvention wherein the springs 6-9 are bolted to the internal surface ofthe frame 3% for the tri-color screen assembly by bolts 61 and 62. As isunderstood by those skilled in the art the spring 69 could also beattached to the frame 30 by means of a weld or by being fitted.

Referring now to Figure 7 there is shown a possible orientation for thetarget support means described in connection with Figures 2 through 6.In this orientation the support means are arranged at positions 70, 71and 72 which are arranged 120 from each other within the cathode raytube 10. Other orientations may also be used as well as a larger orsmaller numbers of support means. However, for the sake of economy thesmallest number that results in rigid support of the screen assembly 20is desirable. Therefore, three supporting positions as shown in Figure 7are preferable. As can be seen when support positions 79, 71, and 72 areutilized movement of the target assembly is eliminated. Due to thegrooves in the support posts no rotational movement is possible, i. e.the target is oriented or indexed within the tube 10. Furthermoremovement of the target assembly transverse the axis of the tube is alsoeliminated by the tensile properties of the springs and the fact that inorder for the target to move two of the springs must move out of theirrespective grooves.

What is claimed is:

1. A cathode-ray tube comprising, an envelope, said envelope havingsupporting means within said envelope, an apertured member, spring meanssecured to said apertured member, said spring means being in contactwith and supported by said supporting means said supporting means andsaid spring means having interengaging index means for determining theangular orientation of said apertured member with respect to saidenvelope.

2. A cathode-ray tube comprising, a glass envelope having supportingmeans comprising recesses spaced around the axis of said envelope, anapertured member within said envelope, resilient springs secured to saidapertured member, each of said resilient springs being under compressionand engaging one of said recesses.

3. A cathode-ray tube comprising, a glass envelope including a targetassembly having outwardly extending resilient support members thereon,mounting lugs integral with the inner surface of said envelope andpositioned around the axis of said envelope and each of said supportmembers engaging a pair of said lugs.

4. A cathode-ray tube comprising, a glass envelope having a neck portioncontaining an electron gun, and a main chamber containing a targetassembly, said target assembly having a plurality of circumferentiallyspaced outwardly extending resilient support members thereon, aplurality of circumferentially spaced inwardly extending glass supportmeans integral with the inner surface of said envelope and receivingsaid resilient support members whereby said target assembly isresiliently supported in a predetermined radially oriented spacedrelationship with respect to said envelope.

5. A cathode-day tube assembly comprising an envelope, said envelopeincluding a frustrum portion having a glass face panel closing thelarger opening thereof and a neck portion including at least oneelectron gun closing the smaller opening thereof, a target assemblywithin said envelope and arranged adjacent said face panel, resilientsupport means connected to said target assembly, and indexing meanswithin said envelope receiving a portion of said resilient support meansto resiliently support and index said target assembly within saidenvelope.

6. In a cathode-ray tube assembly, a hollow frustrum forming a portionof the envelope for said cathode-ray tube, a glass neck portion closingthe smaller opening of said frustrum and forming a portion of saidenvelope, a glass face panel closing the larger opening of said frustrumand forming a portion of said envelope, a plurality of indexing meansmounted in circumferentially spaced array on the inner surface of saidenvelope and adjacent said larger opening of said frustrum, a targetassembly, resilient members arranged in substantially the samecircumferentially spaced array as said indexing means and connected tosaid target assembly, and said resilient members being supported by saidindexing means, whereby said target assembly is resiliently supportedwithin said envelope.

7. A cathode-ray tube assembly comprising, a glass envelope, a pluralityof pairs of grooved glass support posts mounted in circumferentiallyspaced array on the inner surface of said envelope and adjacent thelarger end thereof, a target assembly, resilient springs mounted incircumferentially spaced array on said target assembly, the spacing ofsaid support posts and the spacing of said springs being substantiallythe same, each of said springs being in contact with and supportedbetween a pair of said support posts while under compression, wherebysaid target is resiliently suspended Within said envelope and radiallyoriented with respect to said envelope.

8. A cathode-ray tube assembly as in claim 7 wherein each of saidsprings are connected to said target assembly by a single connection,and said single connection is substantially in the center of said targetassembly with each of said springs extending outwardly therefrom andcurving back toward said target assembly.

9. A cathode-ray tube assembly as in claim 7 wherein the ends of each ofsaid springs are connected to the external surface of said targetassembly with the balance of each of said springs extending outwardlytherefrom.

10. A cathode-ray tube assembly as in claim 7 wherein the ends of eachof said springs are connected to the internal surface of said targetassembly, each of said springs extending from one of said connectionsaround the external surface of said target assembly and back to theother of said connections.

References Cited in the file of this patent UNITED STATES PATENTS2,123,957 Orth s- July 19, 1938 2,195,444 Brett Apr. 2, 1940 2,425,980Baird Aug. 19, 1947 2,546,828 Levy Mar. 27, 1951 2,661,437 Beckers Dec.1, 1953

